Kogoro, Ran, and Conan go to Cafe Poirot in the morning for breakfast. Kogoro barges in before the shop actually opens causing Azusa to be angry. She, however, welcomes Ran and Conan to come in as well. Azusa uses IoT (Internet of Things) to control the electric kettle to boil water sometime before they reach the cafe. As they have breakfast, an issue seems to be happening with Amuro's cake. Last night when he prepared it, it was perfect but this morning it has melted. The Detective Boys call Conan using the Detective Badge informing him of the Professor's latest invention, a drone. While the communication is taking place, the rotors of the drone suddenly start spinning and it flies and crashes into the roof causing Agasa to be disappointed. He goes inside to fix the drone. Conan witnesses the panic on the other side.

The electrician is called for fixing the refrigerator but he claims that there is nothing wrong with it. Ayumi after eating the cake runs to a nearby restaurant which sells cakes suspiciously similar to Amuro's, but taste completely different with Amuro's being more delicious. The Detective Boys claim that someone in the restaurant probably ruined Amuro's cake to make their sales bigger. Conan, drove by his own curiosity as well as the Detective Boys persuasion, installs his phone to record footage of Cafe Poirot during the night. Nothing suspicious is seen in the footage.

Azusa says that the cake only melts two out of every three days. Conan continues to capture footage and finds that the days the cake melted corresponds to a car passing by the cafe the night before, of which the reflection is seen in the windows of the cafe but the inside of the cafe can not be seen.

Conan explains the phenomenon of the cake melting by the concept of wave interference. The taxi that passed by the cafe used radio waves which had the same frequency as used by the electric kettle, which caused the kettle to boil the water in it and emit steam near the refrigerator air inlet vent. This caused the hot air to enter the refrigerator thereby melting the cake. This was also the reason why they couldn't see the inside of the cafe through the glass during the days the cake had melted due to the water vapour sticking to the interior surface of the glass. Coincidentally, this was also the reason Agasa's drone started flying by itself because the frequency of the Detective Badge used by Mitsuhiko to communicate with Conan was the same as the radio wave frequency used by the drone to communicate with it's remote controller.

When he said that he already has a plan to solve the problem, Amuro originally planned to make the cake such that it wouldn't require refrigeration instead of solving the mystery of the melting of the cake. He finally succeeds in his attempt by half-baking the cake and putting the frosting of cream and yogurt and fruit on top of it before serving, which is greatly complimented by everyone including Conan.

Kogoro exclaims that he forgot the real reason he returned to the cafe. He hands out a government-issued notice. Some of the roads will be closed temporarily due to the event of Tokyo Summit being held on May 1st. Amuro has also taken leave from Cafe Poirot for that day. Conan says that after all, he wasn't disregarding his duty as a Public Service Officer.

Conan's final words are: "At that time, I had no idea the Amuro, who was enjoying baking cakes over solving cases, would do something like that." This hints towards the plot of movie 22 where Amuro seemingly turns against Conan. The final scene shows a lighthouse emitting light beams with the city in the background.

The episode's scripwriter, Takeharu Sakurai, stated in an interview that the anime production team requested that the episode only be about food, and contain no murder. This was also the case for Sakurai's last two filler episodes movies' prologue, The Missing Sweets in the Old Shop and The Shadow Approaching Amuro. Munch's Missing Scream being the only exception.